A fan club is a group that is dedicated to a well-known person, group, idea (such as history) or sometimes even an inanimate object (such as a famous building). Most fan clubs are run by fans who devote considerable time and resources to supporting them. There are also "official" fan clubs that are run by someone associated with the person or organization the club is centered on. This is the case for many musicians, sports teams, etc.
Today, many fan clubs have web sites to support their adoring efforts. These sites usually have photos and information on the object of their affection. For example, a fan site dedicated to musicians might have photos, videos, discussion boards, and information on upcoming concerts.